Research On The Plasticizers Of Starch Sizing Agents

Because of the fragility of starch flim, makes the starch film of sizing surface break off easily, has poor integrity and weak protection of sizing. These would harm the quality of sizing greatly, particularly in the age of high-speed sizing after reducing the amount of PVA. Therefore, in this paper, the effcts of amino and hydroxyl plasticizers on the plasticization of starch sizing agents, the inherent law of the plasticizatrion, the better plasticizer, and the reasonable content was investigated, in order to meet the demand of starch plasticization in non-PVA-containing size formulation, and to improve the fragility of starch film and the sizing performance of starch sizing agents.Firstly, effect of some amino substances used as plasticizers on the plasticization of starch sizing agents was investigated in terms of paste viscosity, viscosity stability, adhesion-to-fibers, and starch film behaviors. The experimental results demonstrated that the plasticizers could improve the fragility of starch film because breaking elongation and flex resistance of the film increased and wear loss decreased. However, tensile strength of the film decreased with the increase of plasticizer content. It was recommended that monoethanolamine should be used for plasticizing starch with a content of 6%-9% based on dry weight of starch.Secondly, In order to reveal the influence of number of hydroxyls in molecules of hydroxyl-containing plasticizers on the plasticization for starch sizing agents, plasticization of the plasticizers was investigated through control test. The plasticization was evaluated in terms of extension of starch film. And end-use ability of the plasticizers was accessed through film performances, adhesion-to-fibers, and paste behaviors (viscosity and its stability). Experimental results demonstrated that the plasticizers all exhibited plasticization for starch sizing agents, and could reduce the shortcomings such as film rigidity and brittleness of starch. The plasticizers enhanced the plasticization of starch with increasing number of hydroxyls up to 3, reaching maximal effect, and beyond this number it reduced again. Glycerol and 1,1,1-trimethylolpropane showed the most marked plasticization for plasticizing starch sizing agents among the plasticizers considered. For this reason, these two plasticizers were recommended in uses as the plasticizers of starch sizing agents.At last, the plasticization of 1,1,1-trimethylolpropane for starch sizing agents was investigated in terms of extension of starch film. In addition, the effects of the plasticizer on paste viscosity, viscosity stability, and adhesion-to-fibers were also considered so as to evaluate the probability of the plasticizer in warp sizing. Reasonable ratio of 1,1,1-trimethylolpropane to starch was determined in accordance with experiments. The results indicated that 1,1,1-trimethylolpropane had evident effect on the plasticization of starch sizing agents. As the ratio of 1,1,1-trimethylolpropane to starch increased, the plasticization enhanced initially, reached maximum at the ratio of 5%, and then reduced. It was recommended that reasonable molar ratio of 1,1,1-trimethylolpropane to starch in warp sizing operation was 5% based on our experiments, meanwhile the hygroscopic of the plasticizing starch film of 1,1,1-trimethylolpropane was lower than glycerol, so it would avoid the problem of moisture-stick of the plasticizing starch film of glycerol, could increase the efficiency of loom, improve the quality of sizing greatly.